Nothing is "free" in this world, every added feature will have some cost in memory or fps, and VRAM in V5 is precious but, we promised to deliver multi-liveries in V5 a while ago, so it had to be done.
So, it's not that VRAM has really "increased", it just went back to what it always was with P3D4 (or even FSX), which always had multi-liveries. Probably even less than P3D4, because other VRAM-consuming things like Jetway numbers or custom textures are still not supported.
And, it depends on how the GSX profile for an airport is made. If you set up a different handler, a different catering logo and a different jetway logo and a different jetway model for EACH gate, and the airport has many of them, it will of course take more VRAM that having less different textures and/or jetway models loaded at the same time.
But again, that would have been exactly the same in P3D V4, the only difference is that with DirectX 12 and V5, VRAM handling is more in the hands of the application instead of Direct X+video drivers, which means users should be more careful with their settings.
If you create a custom GSX profile for an airport to use default handlers everywhere and disable all jetway logos, it will take about the same amount of VRAM as before the update.